While
We use while + subject + verb:
Subject + verb
I fell asleep while I was watching television.
We met a lot of interesting people while we were on holiday.
Robert suddenly began to feel ill while he was doing the examination.
Some more examples of while:
We saw Amanda while we were waiting for the bus.
While you were out, there was a phone call for you.
Christopher read a book while I watched television.
When you are talking about the future, use the present (not ‘will’) after while:
I’ll be in London next week. I hope to see Tom while I’m there. (not ‘while I will be there’)
What are you going to do while you are waiting? (not ‘while you will be waiting’)
You cannot use as for time in sentences like this. You have to use while
The doorbell rang while we were asleep. (not ‘as we were asleep’)
You can also use –ing after while
Jim hurt his arm while playing tennis.
The same thing happens after: while
I’m going to read a lot of books while I’m on holiday. (not ‘while I will be’)